Mattress



FIG. 1 is a top plan view of a mattress showing my new design, the undisclosed bottom being plain and unornamented;

FIG. 2 is a side elevational view thereof, the opposite side being identical in appearance;

FIG. 3 is an end elevational view thereof, the opposite end being identical in appearance; and

FIG. 4 is a top, side and end perspective view thereof. 

The ornamental design for a mattress, as shown and described. 